Grinding apparatus for fibrous material

ABSTRACT

Grinding device, more especially a disc refiner for the paper industry, which grinding device comprises, in a housing having two end covers, a rotor and a stator which is displaceable axially relatively to the rotor and which is guided radially but non-rotatably relatively to the housing in guideways on the housing, which stator is connected to a cylindrical part which is coaxial with the stator and with the grinding device and which extends outwardly through a central opening in one of the end covers and is sealed off relatively to the central opening, the improvement that said guideways for said stator are situated outside the range of the stock to be ground.

United States Patent [1 1 [111 3,841,573 Kahmann Oct. 15, 1974 [541GRINDING APPARATUS FOR FIBROUS 2,971,704 2/1961 .lohansson 241 2591 x MERI L 3,212,721 10/1965 Asplunt et a1. 241/37 3,717,308 2/1973 Reinhall241/244 [75] lnventor: Albrecht Kahmann, Weingarten,

. Germany Primary ExaminerRoy Lake [73] Assigne'e: Escher WyssG.m.b.l-l., Ravensburg, Assistant Examiner-Heward Goldberg GermanyAttorney, Agent, or Firm-Robert A. Ostmann [22] Filed. Sept. 14, 1972ABSTRACT [211 App!- 288944 Grinding device, more especially a discrefiner for the paper industry, which grinding device comprises, in a[30 Foreign Appncation priority Data housing having two end covers, arotor and a stator Swt 17 1971 Germany 2146547 which is displaceableaxially relatively to the rotor and which is guided radially butnon-rotatably relatively to [52] U S U 241/245 241/259 2 the housing inguideways on the housing, which stator [51] 7/06 B026 7/1'4 is connectedto a cylindrical part which is coaxial with [58] Field 245 5 1 259 2 thestator and with the grinding device and which ex- 5 25 3 tends outwardlythrough a central opening in one of the end covers and is sealed offrelatively to the cen- [56] References Cited tral opening, theimprovement that said guideways for said stator are situated outside therange of the stock UNITED STATES PATENTS to be ground 2,412,680 12/1946Fisher et a1. 24l/259.l 2,930,534 3/1960 Baxter 241/2591 x 3 Clalms, 1Drawing Figure 20 13' 11; 5, 1. 4 5 22 Q 19 6 i L L j g 1 8 F'T} L 1151:; 1o 7 .J

1 s E 23 13 12 L 6% 1 B GRINDING APPARATUS FOR FIBROUS MATERIALBACKGROUND OF THE INVENTION The invention relates to a grinding device,more especially a disc refinerfor the paper industry, which devicecomprises, in a housing having two end covers, a rotor and a statorwhich is displaceable axially rela' tively to the rotor and which isguided radially but nonrotatably in relation to the housing in guidewayson the housing, which stator is connencted to a cylindrical part whichis coaxial with the stator and the grinding device, the said partextending outwardly through a central opening in one of the end coversand being sealed'off relatively to the central opening.

Such grinding devices are used in the paper industry for preparing thestock to be treated in a paper machine. Since the guideways in the knownconstructions are arranged on the periphery of the displaceable statorin the housing, the fibres which are inthe stock cause a clogging of theguideways. In time, the displacement of the stator for the mutualadjustment relatively to the rotor is blocked and as a result it becomesnecessary to stop the grinding device.

Constructions are also known in which the stator is guided by means ofrods which are perpendicular to it and which are mounted for slidingmovement in the end cover. The deposited fibres also remain adhering tothese rods and in time block the displacement.

The worst feature with all prior constructions is that the blockingaction is not even at the separate guiding points and the stator assumesan angle and thereby becomes jammed. Since strong pressuresare used forthe displacement, this leads to serious damage to the grinding device.

SUMMARY OF THE INVENTION The invention has for its object to increasethe freedom from disruption and the effective life of the grindingdevice.

According to the invention, this object is achieved by the guideways ofthe displaceable stator being disposed outside the range of the stockwhich is to be ground.

This is achieved in advantageous manner by the guideways being arrangedon the outside of the end cover and being connected to the cylindricalpart by connecting elements lying outside the range of the stock whichis to be ground, and advantageously the guideways are arranged withcircular symmetry around the axis of the grinding device and withadvantage each guideway comprises a sleeve which is parallel to the axisof the grinding device and a bolt mounted for displacement in the saidsleeve, the guideways being connected by arms to the cylindrical part.

BRIEF DESCRIPTION OF THE DRAWING One constructional example of theinvention is hereinafter more fully described by reference to theaccompanying drawing.

The drawing shows a grinding device according to the invention inlongitudinal section.

DESCRIPTION OF THE PREFERRED EMBODIMENT The shown device is atandem-disc refiner, which comprises a rotor 4 in a housing 1 which hasa first end cover 2 and a second end cover 3. The rotor 4 is supportedby means of a shaft 7 between a stator 5which is fixed on the end cover2 and a displaceable stator 6. The shaft 7 is mounted in a bearing block8 so as to be fast radially of the housing 1 but axially displaceable,and is sealed off. It is connected while being axially displaceable to adriving motor (not shown). The displaceable stator 6 is formed with acentral opening9 and is connected by means of spokes 10 to a cylindricalpart 11 which is coaxial with the stator and the grinding device, thesaid part extending outwardly through a central opening 12 of the endcover 3 and being sealed off relatively to the central opening 12. Thestator 6 is displaceable axially in relation to the rotor 4, but withrespect to the housing 1, this stator 6 is guidedradially andnon-rotatably be means of guideways 13. The guideways 13, of which thoseindicated ad 13' and 13" are visible in the drawing, are situatedoutside the range of the stock which is to be ground. What is understoodby the range of the stock is the region of the passage of I the stockthrough the grinding device. The stock, arriving through the entryopening 14 which opens tangentially into the housing 1, is moved inapproximately helical form in the space between the end cover 3 and thedisplaceable stator 6,.passes through the opening 9 and advancespartially through the gap 15, partially through the rotor 4 formed withopenings 16 and through the gap 17, whereafter it leaves the grindingdevice through an outlet opening 18.

The guideways 13 are arranged on the outside of the end cover 3 and areconnected to the cylindrical part 11 by connecting elements, a bolt 19and an arm 20. These elements 19 and 20 also lie outside the range ofthe stock to be ground. The guideways 13 are arranged, each offset by soas to have circular symmetry around the axis of the grinding device. Inthe longitudinal section, only the guideway indicated at 13' is to beseen. The second, in side elevation, is indicated at 13'. The thirdguideway cannot be seen in the drawing. Each guideway 13 comprises asleeve 21 which is parallel to the axis of the grinding device and isfixed on the end cover 3, and a bolt 19 mounted to be displaceable inthe sleeve 21. The bolt 19 is fixed on the arm 20, which is connected atthe other end to the cylindrical part 11. Because of the arrangement ofthe guideways 13 outside the range of the stock to be ground, the fibreswhich are in this stock are unable to interfere with the freedom ofmovement of the guideways.

The movement of the displaceable stator 6 is assured by means of ahydraulic servomotor 22, of which the piston 23 is connected to thecylindrical part 11. The part 11 serves as a piston rod of the motor 22.

I claim:

1. A grinding device including a housing having two end covers andcontaining a stator disc which is provided with a central opening andwhich, with an adjacent one of said end covers, bounds a space which ischarged with stock during operation of the grinding device, the statordisc being movable axially relatively to a rotor disc with which itdefines a grinding gap and being connected with a cylindrical part whichis coaxial with that disc and the housing and projects from the latterthrough a central opening in said adjacent end cover and is sealedrelatively thereto; a servomotor connected to the cylindrical part andserving to effect axial movement of the stator disc; and guideway means,including cooperating elements connected; respectively with the statordisc and the housing, for guiding adjacent end cover and to saidcylindrical part.

3. A grinding device as defined in claim 1 in which the cooperatingelements of each guideway means comprise a sleeve which is parallel withthe cylindrical part, and a bolt mounted in the sleeve for reciprocationrelatively thereto; and one, element of each guideway means is connectedwith the stator disc through an arm fixed to the cylindrical part.

1. A grinding device including a housing having two end covers andcontaining a stator disc which is provided with a central opening andwhich, with an adjacent one of said end covers, bounds a space which ischarged with stock during operation of the grinding device, the statordisc being movable axially relatively to a rotor disc with which itdefines a grinding gap and being connected with a cylindrical part whichis coaxial with that disc and the housing and projects from the latterthrough a central opening in said adjacent end cover and is sealedrelatively thereto; a servomotor connected to the cylindrical part andserving to effect axial movement of the stator disc; and guideway means,including cooperating elements connected; respectively with the statordisc and the housing, for guiding said stator disc for said axialmovement; and characterized in that there are a plurality of saidguideway means which are distributed equiaNgularly about the axis of thecylindrical part and which are situated outside said space charged withstock, whereby clogging of the guideway means by the stock is precluded.2. A grinding device as defined in claim 1 in which the cooperatingelements of the guideway means are connected, respectively, to anoutside surface of said adjacent end cover and to said cylindrical part.3. A grinding device as defined in claim 1 in which the cooperatingelements of each guideway means comprise a sleeve which is parallel withthe cylindrical part, and a bolt mounted in the sleeve for reciprocationrelatively thereto; and one element of each guideway means is connectedwith the stator disc through an arm fixed to the cylindrical part.